When fossil fuels are burned, several substances are emitted into the environment, including carbon dioxide (CO2), nitrogen oxides (NOx), and sulfur dioxide (SO2). These pollutants can have adverse effects on the environment and human health.

Carbon Dioxide (CO2) is a greenhouse gas, meaning it traps heat in the Earth's atmosphere. This contributes to global warming and climate change, which can lead to a variety of environmental impacts such as rising sea levels, extreme weather events, and habitat disruption.

Nitrogen oxides (NOx) are a group of gases that contribute to the formation of smog and acid rain. Smog can irritate the respiratory system and cause health problems, particularly for people with asthma or other respiratory conditions. Acid rain can damage forests, waterways, and buildings.

Sulfur dioxide (SO2) is a gas that can cause respiratory problems, including asthma and bronchitis. It can also contribute to the formation of acid rain and smog.